The invention pertains to a method for correcting a fuel quantity injected by means of a fuel injection device during operation of an internal combustion engine.
Methods of the type discussed here are known.
In internal combustion engines comprising at least one fuel injection device for injecting fuel into at least one combustion chamber of the internal combustion engine, parameters for actuating the fuel injection device are typically adapted to the conditions present when the engine is new. Especially as a result of wear or cavitation in the area of the fuel injection device, it is possible that, after a prolonged period of operation of the internal combustion engine, an excessive amount of fuel is injected. This is a problem, because the exhaust gas standards, especially upper limits for soot emission, can no longer be met. The fuel consumption of the internal combustion engine also increases as a result. It is possible, prior to the first start-up of the internal combustion engine, to store a calibration curve in an engine control unit, which curve anticipates the change in the quantity of injected fuel over time and correspondingly changes the actuation of the fuel injection device as a function of the operating time. This suffers from the disadvantage that the parameters for actuating the fuel injection device will be changed even if the amount of fuel being injected is not in fact excessive. According to an alternative, it is known that complicated methods can be carried out to determine the actual quantity of fuel being injected and to calculate a corresponding correction by means of intentional variation of the quantity of injected fuel and by observation of the resulting nonuniformity in the rpm's. Methods are also known which make use of complicated models of the fuel injection device, wherein the injected fuel quantities are corrected in particular by detection of the pressure in the accumulator for the fuel to be injected. All of these solutions are very elaborate and complicated.
German Offenlegungsschrift DE 10 2010 035 026 A1 describes a method for correcting the quantity of fuel injected by a fuel injection device in an internal combustion engine, in which a temperature of the exhaust gas of the internal combustion engine is measured, and a reference temperature of the exhaust gas is calculated by means of a temperature model. The measured and the calculated temperatures are compared, wherein the comparison leads to a temperature difference, which is used to determine a corrected value for the quantity of fuel to be injected. This method is cumbersome, because it is based on a complicated temperature model, wherein in particular it is also necessary to take into account a large number of correction variables.